Again, the invention of this application relates to mounting system and will be described in connection with fixture plates and subplates; however, the invention of this application has a much broader application and can be used in connection with a wide range of quick-change systems and even long-term mounting systems, which are known in the art. Mounting systems have been used over the years for a wide range of applications and can be used to quickly and accurately locate and lock a fixture plate to a subplate. In general terms, the mounting systems are comprised of three general components. These include a locating shank, a liner bushing, and a receiver bushing.
The receiver bushing is mounted to the subplate or machine table, and the liner bushing is mounted to the fixture plate. The locating shank is then positioned through the liner and into the receiver to provide both an accurate location and a locking of the fixture plate to the subplate. This locking action typically takes the form of either a threaded engagement or Assignee's BALL LOCK locking system.
As is known in the art, more than one set of the mounting systems can be used to accurately locate the fixture plate to the subplate. In this respect, if a single mounting system is used without any other locating device, the fixture plate would rotate about the shank axis. This would cause the fixture plate to become misaligned with the subplate. Therefore, more than one mounting system is typically used in these mounting arrangements. However, it has been found that the mounting arrangements can include both positioning mounting systems and holding mounting systems. More particularly, in that, the positioning of a fixture plate to a subplate is essentially a two-dimensional orientation; two mounting systems can be used to control the positioning of the fixture plate relative to the subplate. Then, additional mounting systems can be used to help hold the fixture plate relative to the subplate even though these other mounting systems do not control the positioning of the fixture plate relative to the subplate. For these systems that are used for holding only, the liner does not need to be positioned within the fixture plate. Conversely, the opening in the fixture plate just needs to be larger than the shaft portion of the shank to allow the free passage of the shank through the fixture plate. This provides only a hold-down force for this particular mounting arrangement and does not provide for the alignment of the fixture plate relative to the subplate.
While these mounting systems have been affective in the field, they can be costly to produce and install. In this respect, the prior art mounting systems include a receiver bushing that it is bolted to the subplates by multiple fasteners spaced about the receiver axis. As is referenced above, the mounting systems can be used for both securing the fixture plate to the subplate and for alignment of the fixture plate relative to the subplate. When the mounting system is used for alignment, it is important to accurately locate the individual components of the system so that they line up with one another. Thus, the axis of the liner and the axis of the receiver must be aligned to one another as close as possible. Further, this alignment must fall within a certain tolerance for the resulting fixture plate alignment to be within a desired tolerance. As a result, each machining operation used to create the mounting opening for the receiver bushing must be aligned to specified tolerances. By utilizing multiple fasteners to hold the receiver bushing within the subplate, multiple machining operations are necessary to cut the threads needed to receive these multiple fasteners within the subplate. Further, these cut threads must be aligned with the opening in the receiver bushing. While the position of the cut threads may not be critical in all uses of the mounting system (such as mounting systems used only to hold down the fixture plate), the drilling of the holes and cutting of the threads are still time consuming and adds considerable labor cost to the installation of the mounting system. Further, the use of fasteners spaced about the receiver axis only provides spaced hold-down force about this axis and can weaken the receiver wall in that holes must be drilled therethrough to allow the passage of these fasteners. Further, there is a competing interest between increasing the number of fasteners to increase the hold-down point and the weakening of the receiver wall. It has been found that three fasteners provide the best balance between contact points, installation cost, and weakening the receiver wall.